None of said bonds shall be authorized except upon a finding by the State Bond Commission that there has been filed with it a request for such authorization, which is signed by or on behalf of the Commissioner of Transportation and states such terms and conditions as said commission, in its discretion, may require. Each series of said bonds shall be authorized by a written determination which is signed by a majority of the members of the State Bond Commission and filed in the office of the Secretary of the State and sets forth the principal amount of the bonds of such series and a description of the purpose for which such bonds are authorized. Such description may specify a particular highway project or particular highway projects but shall be sufficient if made merely by a reference to one of the numbered subdivisions of subsection (a) of section 13a-176.